So-called perpetual calendars are known in the prior art in various forms. Such calendars, unlike the every day single year calendar, can be used on a continuing basis up to any year which represents the future limit of the calendar's finite range, such as the year 1999.
The prior art perpetual calendars, like other calendars, simply have the ability to display consecutive dates over a long range of time and are not constructed and operated to display or discover a past or future date on the basis of a date being displayed at any given time. This inability is due to the fact that the prior art calendars are not based in their construction and operation on an existing relationship between the days, months and year numbers, which relationship is recognized in the present invention and forms the basis of the enlarged ability of the calendar to display not only consecutive dates, like any other calendar, but also to display any past or future date in terms of weekday, month and year. This increased utility does not require calculation by the user of the calendar, and only requires a very simple manipulation of moving components.
In accordance with the invention, the stated objectives of the invention are realized through provision of a very simplified arrangement of relatively movable parts which are inexpensive to manufacture and convenient to operate. In a preferred form, the calendar comprises a shallow housing whose upper panel contains display apertures for dates and access slots and apertures for a calendar driving and locking device. Within the housing closely below the display panel are arranged endless belts bearing date indicia with the belts in an operational relationship enabling the desired usage of the calendar with very simple manipulations and without calculation, as previously stated.
Other features and advantages of the invention will appear to those skilled in the art during the course of the following detailed description.